Fig. 4: Effects of inverted cell growth polarity on segregation of chromosomal origins.
a Time-lapse fluorescence microscopy images of Rm2011 mVenus-rgsS wild type and its amiC mutant derivative, carrying parB-cerulean at the native genome location, growing on MM-agarose. Red and black arrowheads indicate accumulation of mVenus-RgsS at the old cell pole of the daughter cell (red) or a mother cell (black). Blue and orange arrowheads show complete (blue) or incomplete (orange) ParB-cerulean focus relocation to the opposite cell pole of a cell with inverted growth polarity. Time is shown in minutes. Scale bar, 2 µm; Ph phase contrast. The images are representative of three independent cultivations and microscopy analyses. b ParB-cerulean focus migration towards the new cell pole in cells with mVenus-RgsS focus at the old cell pole. n, total number of analyzed cells. The values represent the mean values of three biological replicates. The standard deviation values and statistic comparison between the strains are shown in Supplementary Table 7. c Schematic representation of ParB-cerulean spatiotemporal patterns observed in a. In case of cells with normal growth polarity, newborn cells contained a ParB-cerulean focus marking oriC1 at the old cell pole and the migration of a second ParB-cerulean focus marking oriC2 proceeded towards the growing cell pole. In cells with inverted growth polarity, which accumulated the Rgs proteins, which are considered markers for the PG growth zones, at the old cell pole, the migration of the second ParB-cerulean focus marking oriC2 proceeded towards the non-growing cell pole. This resulted in either complete (blue arrows) or incomplete (orange arrows) polar relocation of the second ParB-cerulean focus. A part of the cells that inherited a ParB-cerulean focus at the new cell pole accumulated mVenus-RgsS at the former non-growing pole (black arrow). The color coding is consistent with a. D daughter cell, M mother cell.
